While in office, Thelian had a château built in the Loire Valley to serve as his home. Château Thelian, as it came to be known, became the official residence of the Federation President, used by and containing portraits of every president after Thelian.

By 2380, Thelian was the oldest surviving former president of the United Federation of Planets. Upon the death of Jaresh-Inyo of Grazer that year, he was one of only two living former presidents, the other being Amitra. The elderly Thelian's poor health prevented him from attending Jaresh-Inyo's state funeral on Mars. (STnovel: Articles of the Federation)

The dating of Enter the Wolves established Thelian served at least one term in office from 2325 to 2328; other dates given in the succession box below are conjectural.

President Thelian is depicted in Enter the Wolves wearing a Starfleet uniform, even though he would have had to leave Starfleet in order to run for office (as per Articles). One possibility is that he wore his uniform on formal occasions in lieu of Andorian formal dress, as is his right as a former officer.